Wireless communication systems have developed through various generations, including a first-generation analog wireless phone service (1G), a second-generation (2G) digital wireless phone service (including interim 2.5G networks) and third-generation (3G) and fourth-generation (4G) high speed data/Internet-capable wireless services.
More recently, Long Term Evolution (LTE) has been developed by the 3rd Generation Partnership Project (3GPP) as a radio access network technology for wireless communication of high-speed data and packetized voice for mobile phones and other mobile terminals. LTE has evolved from the Global System for Mobile Communications (GSM) system and from derivatives of GSM, such as Enhanced Data rates for GSM Evolution (EDGE), Universal Mobile Telecommunications System (UMTS), and High-Speed Packet Access (HSPA).
In North America, wireless communications systems, such as LTE, use a solution for Enhanced 911, or E911, that links emergency callers with the appropriate public resources. The solution attempts to automatically associate the caller, i.e., the caller's user equipment (UE), with a specific location, such as a physical address or geographic coordinates. Automatically locating the caller with high accuracy (e.g., with a distance error of 50 meters or less) and providing the location to a Public Safety Answering Point (PSAP) can increase the speed with which the public safety side can locate the required resources during emergencies, especially where the caller may be unable to communicate his/her location (e.g. does not know the location or is unable to speak adequately). Accurately locating a user of a UE for other reasons can also be useful or important—e.g. to provide navigation assistance or direction finding to the user or to enable tracking of the user (or the UE) by another authorized user.